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Species Diversity and Key Innovations

The role of pollination syndromes as key innovations in plant speciation and diversification is a subject of much interest and controversy. Increasing amounts of genomic data are available for not only determining relationships among organisms, but also investigating the time frame in which these organisms have evolved. As sophisticated molecular-clock algorithms are used to accurately estimate ages of organismal speciation and diversification, robust statistical techniques have been developed to estimate absolute rates of diversification for independent lineages. Diversification rates are then compared with physical, physiological, or ecological attributes of organisms to investigate the role of any particular acquired characteristic (key innovation) on subsequent rates of speciation.

Studies of key innovations within the monocot family Costaceae indicate that specialized relationships with animal pollinators have led to increased rates of diversification (i.e. rapid radiations) in the two bird-pollinated lineages. Research in the lab expands upon this work with Costaceae to include all Monocot lineages, where elaborate pollination systems involving birds, insects and mammals have evolved multiple times. The Monocots comprise a major component of both tropical and temperate ecosystems and include agriculturally (e.g. grasses) and horticulturally (e.g. orchids) important plants, making them an ideal model system for this type of analysis.

We are currently analyzing rates of speciation with information on pollinator specificity to test hypotheses concerning the influence of pollinator-specific associations on diversification across major lineages at multiple ecological and temporal scales. The results of this research will help to determine the effect of pollination-specific floral structure and pollinator specificity on species diversification rates in both temperate and tropical environments. Such information is crucial to understanding the role of pollination and the effect of pollinator specificity on biological diversification and species radiations in all plants. Part of this work was published in The Botanical Review 2012.